Flexible LED light strings have been widely used, playing important roles in household and businesses illumination areas. In an early stage, a typical method for making such flexible LED light strings includes inserting a flexible printed circuit board (PCB) with LED light beads surface-mounted into a silicone tube or a polyvinyl chloride (PVC) transparent tube, followed by heating the silicone tube or the PVC tube, causing it to shrink, so as to form a flexible LED light string. Such a method is suitable for producing the products with a simple structure only, as the coating process, i.e., coating the heat shrinking tube on the flexible LED PCB, cannot be easily controlled. In addition, for products having a complicated structure and multiple colors on the outside surface, its application is constrained, as the resulting products may be aesthetically unappealing and its production efficiency is low.